Radiation

Question 1

What is proton number?

Answer 1

Proton number, Z, is also known as the atomic number, represents the number of protons of an element

Question 2

What is nucleon number?

Answer 2

Nucleon number, A, is also known as mass number, is the total number of neutrons and protons in the nucleus of an atom

Question 3

What are isotopes?

Answer 3

Isotopes are atoms of the same element that have the same number of protons but different number of neutrons

Question 4

What is impossible to measure relating to radioactivity?

Answer 4

• make the radioactive nucleus emit radiation by heating, cooling, or any other methods.
• predict when radioactive nucleus will emit radiation.
• know the direction in which emitted radiation will leave a nucleus

Question 5

What is radioactive decay?

Answer 5

It is a random and spontaneous process by which an unstable atomic nucleus loses its energy by emission of electromagnetic radiation or particle(s).

Question 6

What is an alpha particle?

Answer 6

An alpha particle consists of two protons and two neutrons tightly bounded together.

Question 7

What is a beta particle?

Answer 7

A beta particle is a fast-moving electron ejected from a radioactive nucleus.

Question 8

What is a gamma ray?

Answer 8

An gamma ray is electromagnetic radiation emitted by a radioactive nucleus with excess energy

Question 9

What happens to atom during alpha decay?

Answer 9

• nucleus emits an α-particle (identical to helium nucleus
• nucleon number decreases by 4 and proton number decreases by 2
  For example: radium emits an α-particle, decays to radon

Question 10

What happens to atom during beta decay?

Answer 10

• nucleus emits an β-particle (an electron)
• nucleon number remains the same and proton number increases by 1
  For example: carbon-14 emits a β-particle, decays to nitrogen

Question 11

State ionising effect from highest to lowest.

Answer 11

alpha particles, beta particles, gamma rays

Question 12

State penetrating ability of alpha particle

Answer 12

• Least
• Easily absorbed by a piece of paper, a thin aluminium foil or human skin

Question 13

State penetrating ability of beta particle

Answer 13

• Medium
• Absorbed by a piece of aluminium foil that is a few millimetres thick

Question 14

State penetrating ability of gamma ray

Answer 14

• Highest
• Passes through most materials easily but absorbed by lead that is a few centimetres thick or very thick concrete

Question 15

State artificial and natural sources of background radiation

Answer 15

Artificial
- Medical X-Rays
- Building Materials
- Waste products from nuclear power plants
Natural
- Rocks
- Radon gas in the air
- Food and drink (food high in potassium like bananas, carrots)

Question 16

Define half-life

Answer 16

The half-life of a radioactive nuclide is the time taken for half the remaining unstable nuclei in a radioactive sample to decay.

Question 17

Define nuclear fission

Answer 17

Nuclear fission is a process in which the nucleus of an atom splits and releases a huge amount of energy

Question 18

What occurs during nuclear fission in terms of energy transfer and atoms

Answer 18

• During nuclear fission, the original atom (parent nucleus) becomes atoms of 2 different elements (daughter nuclei)
• Energy is transferred from nuclear store of unstable nucleus to
  
  • the kinetic, internal and nuclear stores of the daughter nuclei and neutrons
  • the internal store of the surroundings (to heat water into steam, which will turn turbine to generate electricity)

Question 19

Define nuclear fusion

Answer 19

Nuclear fusion is a process in which 2 light atomic nuclei combine to form one heavier atomic nucleus and releases a huge amount of energy.

Question 20

State the uses of nuclear fusion in nuclear power plants

Answer 20

• In nuclear power plant, nuclear fuel (eg: uranium and plutonium) undergo nuclear fission to release energy, in a self-sustaining chain reaction that is controlled.
• Nuclear fusion is not used in nuclear power plants as it requires very high temperatures and pressures.

Question 21

State the uses of radioactivity related to cell damage

Answer 21

• Medical: γ-rays for detection of tumours and destroying brain tumours; β-particles for treatment of thyroid disorder
• Safety: γ-rays for killing microbes, sterilising medical equipment,

Question 22

State the uses of radioactivity related to radioactive decay and half-life

Answer 22

• Geology: α-particles to determine how old an object is

Question 23

State the uses of radioactivity related to penetrating abilities and ionising effects:

Answer 23

• Safety: α-particles in smoke detector
• Industrial: γ-rays or β-particles to measure thickness of materials

Question 24

What are hazards of radioactivity?

Answer 24

Hazards of radioactivity can kills cells, cause cells mutation and cancer, and stunt children’s growth in human; plants and animals can suffer from mutations, stunted growth and reproduction defects.

Question 25

How do we limit contamination to radioactive accident?

Answer 25

• leave area quickly
• remove the outer layer of clothing
• wash all exposed parts of body with soap and lukewarm water

Question 26

How do we reduce exposure to ionising radiation?

Answer 26

• reduce exposure time
• increase distance between source and living tissue
• use shielding (eg: lead-lined gloves and suits
• proper storage of (eg: store and label radioactive substance in a lead box)